Smart shelf readers represent an emerging technology wherein articles of merchandise presented for sale in a retail establishment are each equipped with a radio frequency identification (RFID) transponder, or “tag” as the transponders are known in the art. These smart shelf readers are capable of determining the number, identity, and location of multiple tagged merchandise items placed on a store shelf, book shelf, or other display fixture. When these shelves or other fixtures are equipped with one or more antennas coupled to an RFID interrogator, the contents of each merchandise item's tag may be read by the RFID interrogator. By reading the tags on the merchandise items, store management can obtain a wealth of information.
First, the count and/or location of each inventory item may be obtained and, consequently, out of stock situations may be avoided. Keeping shelves stocked with product no longer depends on an employee's periodic visual scanning of shelves and initiation of a restocking activity since a computer inventory control system coupled to the smart shelf system can intelligently initiate restocking. Reordering of products may also be handled semi- or fully automatically based upon information from the smart shelf system.
Misplaced items (e.g., items picked up by a shopper and later randomly set down at a location in the store other than where the item belongs) may be readily located and included, if desired, in the real-time inventory.
Smart shelf systems may also provide easy and/or early detection of pilferage.
Shopper preference information may be readily obtained by recording the number of times a particular product is picked up and then re-shelved by a shopper. Real time information about product placement may also be obtained. That is, a product's shelf location may be changed and the effect noted in a matter of hours or days rather than at the end of a sales quarter or other relatively long time.
Smart shelf RFID systems of the prior art are subject to several limitations. First, because of the way RFID systems operate, the merchandise itself presents limitations. Package sizes, shapes, and contents vary considerably. Each of these factors presents design challenges. In the past, liquids in the packages have presented particularly difficult obstacles to implementing RFID-based smart shelf systems. Because RFID systems rely on the radio frequency (RF) absorption characteristics of the packages and their contents, liquids often provide very different characteristics from solids or powders. In addition, product spillage, acts of sabotage, and other abuse or neglect of the equipment may impair the ability of an RFID smart shelf system to be kept at peak operating efficiency.
When smart shelf readers are placed in commercial installations, there are several parameters that must be considered. Smart shelf readers are generally used with an array of antennas, typically positioned close to one another.
Often, the tagged merchandise items to be tracked are placed directly on top of these antennas with only a very small gap separating the antennas and the items. Because smart shelf systems are typically designed for general merchandise tracking and monitoring, the interaction between the radiated RF wave and the merchandise must be carefully considered.
Since different packaging can have different RF absorption or reflection characteristics, the type of packaging and the material within the packaging, plus the number of packages on the antenna, will affect the antenna matching. In order to achieve optimum interface in such dynamic and changing environments, the smart shelf readers must be designed to accommodate wide ranges of conditions while maintaining peak circuit interface.